The present invention pertains to equipment used in processing photosensitive material, and more particularly to a door assembly for an autoloader for feeding cassettes and/or pallets containing cassettes to and receiving them from a computed radiographic reader.
It is convenient to handle storage phosphorous film/plates within cassettes that protect the film from extraneous light and damage. Storage phosphorous film is read by photoelectrically detecting an image formed by scanning with stimulating radiation. An example of such a scanner/reader is disclosed in U.S. Pat. No. A-4,789,782 to O'Hara. It is desirable to retain the x-ray film within a cassette except during actual processing. Such a cassette is disclosed in U.S. patent application Ser. No. 800,799, filed Nov. 27, 1991, entitled "X-ray Cassette Having Removable Photographic Element" by Jeffrey C. Robertson, which is incorporated herein by reference. A hook extractor can be used with the x-ray cassette to remove a photographic element and scan the cassette in an x-ray reader. It is desirable to provide an apparatus to automate the presentation of such x-ray cassettes or similar cassettes to the extractor in the reader so that a number of x-ray cassettes could be processed in succession without attention from an operator It is also desirable that such an apparatus be able to accurately position x-ray cassettes and/or pallets containing cassettes sequentially to simplify removal and reinsertion of the photographic elements and that the presentation apparatus be separate from the x-ray reader to permit interchange of units and reduce repair time. An example of a suitable device for presenting cassettes is disclosed in copending application U.S. Ser. No. 902,214 filed Jun. 22, 1992, entitled "X-ray Cassette Positioner" of John C. Boutet et al which is also hereby incorporated by reference. In this reference there is disclosed a positioner/autoloader for use with a plurality of x-ray cassettes and/or pallets containing cassettes which comprise first and second cog belts spaced apart so as to provide a plurality of cassette retaining sites one of which defines a cassette read site for presenting of the cassette to the reader. Access to the loading and unloading sites is obtained through a portal in the cabinet enclosing the mechanism. An access door is provided for allowing access within the cabinet through the portal. The belts are driven such that the cassettes are each individually positioned at the read site for removal of the photosensitive film therein for reading by the reader after which it is returned to the cassette. The positioner allows a plurality of individual cassettes to be stored for automatic supplying to the reader thus freeing the operator to accomplish other duties. With such autoloaders it is important that the device be designed to operate in such a manner so as to minimize any transfer of vibrations from the autoloader to the reader which can adversely affect the reader reading the information stored on the photo stimulable phosphorous film. Thus it is important that the door which allows access to the loading and unloading sites operate in smooth manner with a minimal amount of vibrations. The operator may be carrying a number of cassettes either to or from the reader, therefore, it is also desirable that the door be easy and convenient to use. It is also important that the door not close if the cassettes have not been properly loaded or unloaded from the device or an obstruction is in the path of the door.
In accordance with the present invention there is provided a mechanism for automatically opening and closing the access door to the portal of an autoloader which is designed to minimize transfer of vibrations to the reader which can adversely affect the reading of the photographic element, which is reliable, can monitor if the cassettes have been properly loaded or unloaded, and determine if there are obstructions in the path of the door.